Can a DUI Be Dismissed If Police Did Not Have Reasonable Suspicion to Stop You?
A California DUI investigation does not always begin with an officer seeing someone drive erratically. Sometimes an officer follows a vehicle, pulls the driver over, and only then begins looking for signs of alcohol or drug impairment.
But what if the officer did not have a legal reason to stop the vehicle in the first place?
In California, police generally need reasonable suspicion of a traffic violation or criminal activity before making an investigative traffic stop. If the officer did not have reasonable suspicion, the legality of the stop can become an important issue in the DUI case.
An unlawful traffic stop does not automatically mean the DUI charge disappears. However, evidence obtained as a result of an unlawful stop may be subject to suppression. If important evidence is excluded, the prosecution may have a much more difficult time proving the DUI charge.
For someone facing a California DUI, understanding what happened before the officer turned on the lights can be just as important as what happened after the traffic stop began.
What Is Reasonable Suspicion in California?
Reasonable suspicion is the legal standard that generally allows police to briefly detain someone to investigate possible criminal activity or a traffic violation.
California courts have described reasonable suspicion as requiring specific, articulable facts that, considered under the totality of the circumstances, provide an objective basis for suspecting that the person stopped may be involved in criminal activity. Ordinary traffic stops are treated as investigative detentions.
This does not mean an officer must already have enough evidence to prove a DUI before making a traffic stop.
The officer does not need probable cause to believe the driver is guilty of DUI before initiating the stop. Instead, the officer needs an objectively reasonable basis for the detention.
For example, an officer may have reasonable suspicion if the officer observes:
- A driver crossing over lane lines
- A vehicle running a red light or stop sign
- Excessive or unsafe speeding
- A traffic violation
- Driving behavior that reasonably suggests the driver may be impaired
- Other specific circumstances suggesting a violation of the law
The exact circumstances matter. Courts evaluate the facts surrounding the stop rather than simply accepting an officer’s conclusion that a stop was justified.
Police Cannot Simply Stop a Driver Because They Feel Something Is Wrong
An officer’s instinct or hunch is not necessarily enough to justify an investigative detention. There must generally be an objective basis for the stop.
For example, suppose an officer sees a vehicle leaving a San Diego bar late at night. The officer does not observe speeding, swerving, an unsafe lane change, or another traffic violation. The officer simply decides to follow the vehicle and eventually pulls the driver over because the driver came from a location where people consume alcohol.
The fact that someone left a bar does not automatically establish reasonable suspicion that the person is driving under the influence. The same basic principle can apply to other circumstances where an officer relies on assumptions rather than specific observations.
California courts have emphasized that reasonable suspicion requires specific and articulable facts considered in light of the totality of the circumstances.
That distinction can become extremely important in a DUI defense.
What Happens After an Officer Makes an Unlawful Stop?
An unlawful stop does not automatically result in the dismissal of a DUI charge. Instead, a defense attorney may challenge the legality of the detention and seek to suppress evidence obtained as a result of the unlawful stop.
California Penal Code section 1538.5 provides a procedure for seeking suppression of evidence obtained through an unreasonable search or seizure.
The goal may be to prevent the prosecution from using evidence that was obtained because of the unlawful detention.
That evidence could potentially include observations made after the stop, statements made by the driver, field sobriety test results, preliminary alcohol screening results, or other evidence obtained during the investigation, depending on the circumstances and the applicable legal rules.
What If the Officer Claims There Was a Traffic Violation?
A common issue in DUI cases is whether the officer actually observed the traffic violation used to justify the stop.
An arrest report might state that the driver crossed a lane line, failed to stop completely, followed another vehicle too closely, or committed another traffic violation.
A DUI defense may involve reviewing:
- Dash camera footage
- Body camera footage
- Patrol vehicle video
- Traffic camera footage
- Witness statements
- The officer’s report
- Dispatch recordings
- 911 calls
- Photographs
- Roadway conditions
- The officer’s testimony
Video can be particularly important when the written report does not accurately capture what happened on the road.
For example, a report might characterize a vehicle’s movement as unsafe lane weaving when video shows the vehicle made one brief movement to avoid an obstruction.
Can Police Stop You for a Minor Traffic Violation?
A minor traffic violation can still provide a legal basis for a traffic stop. The fact that the officer was not initially investigating a DUI does not necessarily make the stop unlawful.
If an officer has a lawful basis to stop a vehicle for an observed traffic violation, the officer can generally conduct the traffic stop within the limits of the law. During that interaction, the officer may develop additional facts that create reasonable suspicion of DUI.
That means a defense strategy cannot simply be based on the argument that the officer was really looking for drunk drivers.
The more important question is whether the officer had a lawful and objectively reasonable basis for the initial detention and whether the subsequent investigation remained legally justified.
What If the Officer Says the Driver Was Driving Erratically?
Erratic driving can be important evidence supporting a DUI investigation, but the details matter. Not every unusual movement on the road necessarily establishes reasonable suspicion of DUI.
An attorney may examine questions such as:
- How long did the officer observe the driving?
- What exactly did the officer see?
- How many lane deviations occurred?
- Did the vehicle actually cross a lane line?
- Was there heavy traffic?
- Were road conditions unusual?
- Was there construction?
- Was the driver avoiding an obstacle?
- Did the officer observe an actual traffic violation?
- Does dash camera footage support the officer’s description?
Reasonable suspicion is evaluated based on the totality of the circumstances. That means a single fact rarely tells the entire story.
What Evidence Could Be Challenged After an Unlawful Stop?
If a court determines that the traffic stop violated the Fourth Amendment, the next issue is determining what evidence resulted from that violation.
Depending on the circumstances, a defense attorney may challenge evidence obtained during or after the detention. Potentially relevant evidence can include:
- Statements made to police
- Observations of alleged impairment
- Field sobriety test results
- Preliminary alcohol screening results
- Chemical test evidence
- Admissions about drinking
- Evidence obtained from a vehicle
- Other information obtained as part of the DUI investigation
The legal analysis can become complicated because not every piece of evidence collected after a questionable stop is necessarily excluded.
Courts may consider whether the evidence was actually obtained as a result of the unlawful detention and whether another independent legal basis existed for obtaining it.
That is why a suppression issue requires more than simply showing that the driver believes the officer had no reason to make the stop.
Could Suppressing the Evidence Lead to a DUI Dismissal?
If the prosecution’s important evidence came from an unlawful traffic stop and a court excludes that evidence, the prosecution may be left with insufficient evidence to prove the DUI charge.
In that situation, the case could potentially be dismissed. But an unlawful stop does not guarantee dismissal.
For example, the prosecution may have evidence that was obtained independently of the traffic stop. There could also be evidence from a collision investigation, witnesses, surveillance footage, or other circumstances that the prosecution argues can still be used.
The practical question is therefore not simply whether the stop was unlawful. The bigger question is:
What evidence does the prosecution still have if the challenged evidence is excluded?
How a DUI Attorney Can Investigate the Initial Traffic Stop
The beginning of the police encounter deserves careful attention in any DUI case involving a questionable stop.
A defense attorney may review the police reports alongside available recordings and other evidence to reconstruct what happened before the officer initiated the detention.
That investigation can reveal differences between what an officer reported and what the available evidence shows.
Important questions can include:
- What caused the officer to begin following the vehicle?
- What did the officer observe before activating the emergency lights?
- Did the officer actually see a traffic violation?
- Did dispatch provide information about the vehicle?
- Did another driver report the vehicle?
- Was the officer responding to an accident or other incident?
- When did the officer first suspect DUI?
- When did the officer begin questioning the driver?
- When were field sobriety tests requested?
- When was a breath or blood test requested?
The timeline can be critical because reasonable suspicion must be evaluated based on what the officer knew at the relevant time.
A DUI Stop in San Diego Should Be Examined From the Beginning
A DUI defense does not necessarily begin with the breath test, blood test, or field sobriety tests. It can begin several minutes earlier, with the reason the officer stopped the vehicle.
California law requires an objective basis for an investigative detention. If the initial stop was not supported by reasonable suspicion or another lawful justification, the legality of everything that followed may need to be examined.
The California DMV also treats the administrative license proceeding separately from the criminal DUI case. For an APS action, DMV considers whether the officer had reasonable cause to believe the driver was violating the applicable DUI laws, among other issues. Drivers generally have 10 days after receiving the suspension or revocation order to request an administrative hearing.
That means a DUI arrest can create both a criminal case and a separate DMV matter, each of which may require attention.
A questionable traffic stop can become an important part of a California DUI defense, particularly when the evidence supporting the DUI investigation developed only after police detained the driver.
Whether a stop was lawful depends on the specific facts. An attorney may need to examine the officer’s observations, video recordings, dispatch information, reports, witness accounts, and the precise timeline of the encounter.
If you were arrested for DUI in San Diego and believe the officer had no legitimate reason to pull you over, the circumstances surrounding the initial stop deserve careful legal review. Rick Mueller focuses on California DUI defense and can evaluate the traffic stop, the investigation, and the evidence used against you to determine what legal issues may be available in your case.
Contact Rick Mueller, San Diego DUI Defense Attorney to learn more about defending a California DUI and schedule a free consultation today.